Finally, I have a confession to make. As part of this project, I wrote and tested a complete wrapper for the Win32 Waitable Events API before stumbling on the ManualResetEvent and AutoResetEvent framework classes that already encapsulated all the functionality I needed. Remember:
ugg handbags you just might be spending all your free time writing brand new classes from scratch when just what you needed already existed. Check your local hardware store before reinventing the wheel. On this principle, I hope that the base classes developed here will help other programmers bring RS232 device communications into the .NET world.
LineTerm uses CommLine as its base class and illustrates how to use the library in source code. You will need to run it from the Visual Studio? IDE because there is no user interface for settings. In Visual Studio .
sheepskin ugg boots NET, create a new Visual Basic console application. Remove the supplied default module from the project. Copy LineTerm.vb, CommBase.dll, and CommBase.xml into the project directory (the XML file provides IntelliSense? information for the library). Use Add Existing Item in the project explorer to import LineTerm.vb and Add Reference to set a reference to CommBase.dll. You should now be able to build and run the project.
Here,
ugg boots for cheap wo is a local variable of type Win32Com.OVERLAPPED, and ptrUWO is a private class variable of type IntPtr. Marshal is a static object in System.Runtime.InteropServices that provides access to the interop marshaler. In this code, I am doing manually what the marshaler normally does automatically when an external function is called. The first step is to allocate an appropriately sized block of unmanaged memory, then copy the contents of the managed structure into it,
ugg boots online remapping the memory layout as required. After the function call, the marshaler would normally use Marshal.PtrToStructure to perform the reverse copy, then Marshal.FreeHGlobal to release the memory.
christian louboutin sale I perform this operation manually because of the special way the API uses the OVERLAPPED structure. I will specify it in a WriteFile call, but then the operating system will continue to use it after the call returns.
Once the port is opened and configured, Open invokes a virtual method AfterOpen, which may be overridden to check the status of the connection to the remote device and possibly also to configure it.
christian louboutin booties If this returns false, the port will be closed again and Open itself will return false. There is also a BeforeClose method for shutting down the remote device if necessary.
Use P/Invoke to wrap the API functions, constants, and structure definitions as static members of a managed class. While I use this approach internally, I do not expose this class to application programmers.
christian louboutin boots sale ReceiveThread is an infinite loop of code broken only on an exception. I terminate the thread on closing the port using the following line: This throws a ThreadAbortException in the thread, causing it to terminate via the catch clause, which is used for tidying up. A finally clause could also be used, but in this case it makes is no difference because the only exit route is through an exception.
Since there is currently very little tool support for P/Invoke, I have had to handcraft these definitions. The key resources include the Win32 API documentation and the header files provided for use with C++.
christian louboutin on sale (The excellent file search facilities in Visual Studio .NET are invaluable for finding definitions in the header files. I use these for documentation purposes only; you don't need them to compile the library.) A full discussion of interop marshaling, the process by which managed data types are translated into the unmanaged C definitions used by the API, is beyond the scope of this article. However, you can get an idea of what is going on under the hood from another piece of code in the Open method.
